Intrusion detection fences of the type known as “taut wire warning fence” are already known. A typical sector of a taut wire fence includes a couple of anchoring poles, wherein the distance (i. e., space) between them delineates a sector of the fence. Between each of such couple of anchoring poles the wires of the fence (that might be—but not necessarily—of the barbed wire type) are taut. They are at a designated vertical distance one from the other, thus forming a kind of a virtual surface (a plane), defining an area of parallel horizontal wires that is perpendicular to the ground.
The wires that are taut, as said, between given couples of anchoring poles, form a kind of transmission (or communication) lines that provides indications of the occurrence of an intrusion incident (or an attempted one) through them. A change in the tension in a wire of the fence—such as happens while bending or severing the taut wire, that would happen as a result of an actual intrusion occurrence or an attempted one (for example climbing on the wires, trying to push away parallel adjacent wires in order to increase the distance between them to enable passage or using cutters on them to cut the wires), any such occurrence is “transmitted” as an amenable to be sensed indication through the usually taut wire, like a (musical) “string”.
The amenable to be sensed indication, as an outcome of the change that occurred in the tension of the wire—is received (sensed) by one sensor or more, that is (are) linked to the taut wire. The sensor, in due course, generates (produces) an electrical signal that can be received and analyzed at a remote control center.
An example for such intrusion detection fence of the taut wire fence type, is the commercially available and marketed fence, denoted DTR—that is manufactured and marketed by the applicant of this present patent (check their site—http://www.magal-s3.com/products).
A typical sector of a DTR fence includes plurality of barbed wire cords that are deployed with a distance of nine (9) to twenty (20) cm one from the other, wherein they are taut between a couple of anchoring poles that are located at a typical distance of approximately fifty (50) meters one from the other. A number of sensors are installed on “a sensors' pole” that is positioned approximately at the half point distance located between the two anchoring poles.
In addition, between every two (couple of) anchoring poles, there might be located also one or more “sliding poles”, e.g.—spiral like poles, that enable horizontal movement of the wires on them but at the same time and in all that is concerned with loading the wires for bending, the sliding poles define and delineate relatively small support spaces, in a manner that forces increasing the effort that have to be exerted for bending the wires, and naturally, in a manner that increases the amenability to be sensed variation of the tensions in the bent wire. In a DTR fence, each couple of taut wires is allocated to one sensor and is connected with it. A sensors' pole is installed with six groups of sensors at most, so that the taut wires' plane of the fence might include several “Sensing Slices”. Dividing the height of the pole into a number of “Sensing Slices” enables to run separately an analysis of the received signals from each of the sensors' groups, and in a manner that imparts high capability of identifying an intrusion attempt by climbing on the wires of the fence (for example—indication in a configuration of a continuum of signals from several “Sensing Slices” that are positioned one on the top of the other, and that are received successively, one after the other.
However, the sensors' pole in a DTR fence and the sensors that are installed on it, do not provide signals that enable to identify the exact location in space of the intrusion occurrence as it is related relative to the sensors' pole proper (for example—whether the intrusion attempt that is made by climbing on the fence, as we stated above, is taking place in the taut wires plane positioned to the right of the sensors' pole, or whether it occurs to the left of that sensors' pole).
Moreover, each one of the sensor groups by itself does not enable analyzing the group's produced signals at the specific individual sensor level, because the connection of the sensors in each group is done in series. In other words—the warning that is received relates to a given group of sensors and there exists no capability of discerning which is the single specific sensor that triggers the alarm within a given group.
The sensors that are installed nowadays in a DTR fence are of the “short/cut-off” binary sensors type (bi-state: go/no go). A variation in the tension of whichever wire it is from the couple (two) wires unto which the sensor in the DTR fence is connected, might extract the sensor from the state that it is regularly found in (for our presentation—shorted) and pass it to other state—namely cut-off, in a manner so that the control system that is all the while sampling the status of the sensors, might identify only the fact of the occurrence of an intrusion attempt through the fence, via the specific group of sensors.
A variation in the tension of a taut wire that, as said, brings about a change of state in a sensor (from short circuit to cut-off) is the outcome of actuating a certain weight on the wire unto which that sensor is connected (except in the case of severing (cutting) the wire). In other words, the sensor changes its status at the time that a wire unto which it is connected is loaded beyond a given weight threshold. The level of sensitivity of the sensor is constant (in accordance to the weight unto which the wire is exposed and wherein it is sufficient for switching over the sensor from short circuit state to cut-off).
Thus, the sensors that are installed nowadays in a DTR fence, do not provide (issue) signals that enable to deduce information regarding the value (magnitude) of the weight that is operating on the wire before an alarm is sounded (before the switching over from a short (circuit) state to cut-off), and afterwards (following the sensor's switched from short (circuit) state to cut-off).
The sensors that are installed nowadays in a DTR fence also do not provide indications from which it might have been possible to estimate the way travelled by the wire that was subjected to the variation of the tension, nor the direction of this path (track) in space. At most, it is possible to estimate that the switching over of the sensor from short circuit state to cut-off, is the outcome of the loading of the wire and its bending in the plane of the wires, to within a shift of approximately 10 to 12 cm in a vertical direction (relative to the ground).
As for the sensors, that are as said binary (by-state) “switching over sensors” from connecting to cut-off, the sensors that are nowadays installed in a DTR fence are also not able to identify occurrences of appearance of vibrations in the wires, but only the occurrence of a steady pulling action on the wire as it happens due to loading the wire unto a certain weight (except if it is considered to be cutting the wire).
However, to intrusion efforts through such taut wires fences, there might be accompanying occurrences of vibrations in the wires that do not rise (increase) up to an occurrence of a steady pulling force on the wire (for example, an intrusion act by setting a kind of a rigid frame (window like) on the wires of the fence, thus maintaining their tautness—and as its second stage—cutting the wires that are found inside this frame).
It is important to note, that also the substantial physical size (dimensions) of the sensors that are installed nowadays in the DTR fences, constitute a limitation because it does not enable to deploy them at a beneficial crowded arrangement of taut wires such that variations of tautness on all of them would be amenable to be sensed.
Thus, before the invention that is the subject matter of this application, when using intrusion detection fences of the taut wire genre, it was not feasible to obtain the desired combination of beneficial indications—
Both for the location wherein the intrusion attempt occurs in relation to the sensor (does it occur to its right or rather to its left); determining the specific sensor producing the alarm from the group of sensors to which it belongs, and, as was said—in a dynamic mode and for prolonged time spans—applying to the varying weight unto which the wire is loaded during the time of the intrusion attempt, its direction in space and the path that the wire goes through during the attempted intrusion; as well as indications concerning vibrations appearances unto which the wire might be exposed as a result of the intrusion attempt through it.
An additional drawback, due to the (relatively) large physical dimensions of the sensors, there exists in the intrusion detection fences of the taut wire fence type, a geometrical and packaging constraint limitation from the aspect of the capability of crowded deployment of taut wires with complete utilization of their capability to serve simultaneously—all of them, as an active “communication lines”, transferring indications regarding the occurrences of intrusion attempts through them to the sensors that are connected to them.